US6471844B1 - Process for the isolation of aromatic hydroxycarboxylic acids - Google Patents

Process for the isolation of aromatic hydroxycarboxylic acids Download PDF

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US6471844B1
US6471844B1 US09/743,337 US74333701A US6471844B1 US 6471844 B1 US6471844 B1 US 6471844B1 US 74333701 A US74333701 A US 74333701A US 6471844 B1 US6471844 B1 US 6471844B1
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alkali metal
recited
compound
aromatic hydroxycarboxylic
acid
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Michael Robert Samuels
Ronald M. Yabroff
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Ticona LLC
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EI Du Pont de Nemours and Co
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/02—Preparation of carboxylic acids or their salts, halides or anhydrides from salts of carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/487—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives

Definitions

  • This invention relates to a process for the isolation of an aromatic hydroxycarboxylic acid from its mono- or dialkali metal salts. More particularly, this invention relates to such a process in which these salts are electrodialyzed in the presence of other selected alkali metal salts to reduce overvoltage near the end of the electrolysis. Alkali metals and their hydroxides may be completely and economically recycled in the process.
  • Aromatic hydroxycarboxylic acids and dicarboxylic acids are important components in the manufacture of commercial products.
  • p-hydroxybenzoic acid PHBA
  • o-hydroxybenzoic acid is used to make aspirin.
  • aromatic hydroxycarboxylic acids are manufactured using the Kolbe-Schmitt reaction, which is a reaction of an alkali metal salt of an aromatic hydroxy compound with carbon dioxide, usually under elevated temperature and pressure.
  • the Kolbe-Schmitt reaction has been a standard procedure for the preparation of aromatic hydroxy acids for over 100 years; see for instance A. S. Lindsey, et al., Chem. Rev., vol.
  • the dialkali metal salt of a hydroxycarboxylic acid may also be completely electrodialyzed to the free aromatic hydroxycarboxylic acid, but when one tries to completely electrodialyze these compounds (and as one approaches complete electrolysis), the voltage increases and the current efficiency decreases rapidly. As a result, the process may become impractical and/or uneconomical.
  • Japanese Patent Application 40-11492 describes the electrodialysis of an alkali metal salt of terephthaiic acid to terephthalic acid and an alkali metal hydroxide.
  • Japanese Patent Application 64-9954 describes the electrodialysis of an alkali metal salt of hydroxybenzoic acid.
  • R 1 is arylene
  • t is zero to about 1.90;
  • each M is independently an alkali metal cation
  • H z Q is an anion whose conjugate acid has a pK a of about 2 or less;
  • x is an integer of 1 or more, and z is 0 or an integer of 1 or more, provided that x+z is equal to the total number of negative charges on Q;
  • M has a concentration associated with H z Q at a pH of 2.5 of about 0.03 to about 4 molar;
  • y is about 1.95 to 2.00.
  • FIG. 1 is a front elevational view of the apparatus and their layout as used in the Example and Comparative Example disclosed herein.
  • aromatic hydroxycarboxylic acid means a compound that contains at least one aromatic carbocyclic ring; and at least one hydroxyl group and one carboxyl group, both groups of which are attached to a carbon atom of an aromatic carbocyclic ring. If more than one such aromatic ring is present they may be fused, as in naphthalene, connected by a covalent bond, as in biphenyl, or connected by a divalent group, as in diphenyl ether. There may also be inert groups attached to the aromatic ring(s), such as one or more alkyl groups.
  • Compounds which may produced by this process include p-hydroxybenzoic acid, o-hydroxybenzoic acid, 2-hydroxy-3-methylbenzoic acid, 2-hydroxy-5-methylbenzoic acid, 2,4-dihydroxybenzoic acid, and hydroxynapthoic acid.
  • Preferred products are p-hydroxybenzoic acid, 6-hydroxy-2-napthoic acid, and o-hydroxybenzoic acid; while p-hydroxybenzoic acid is especially preferred.
  • arylene as used herein means a radical with two free valencies to carbon atoms of one or two aromatic rings.
  • hydrocarbylene as used herein means a divalent radical containing carbon and hydrogen.
  • Substituted as used herein means one or more substitutents that do not interfere with the reactions described herein. Suitable substitutents include alkyl and halogen.
  • the starting material for the process of the invention is the corresponding dialkali metal salt of an aromatic hydroxycarboxylic acid or its partially acidified form of the formula (OR 1 CO 2 )H t M 2 ⁇ t , wherein t is 0 to about 1.90, more preferably 0 to about 1.0 and especially preferably less than about 0.1.
  • This compound is then electrolyzed so that the value of t is increased to y which is about 1.95 to about 2.00.
  • Sodium and potassium are the preferred alkali metals, with potassium being most preferred.
  • These dialkali metal salts usually originate as an intermediate product of the Kolbe-Schmitt synthesis of aromatic hydroxycarboxylic acids.
  • the Kolbe-Schmitt process starts with alkali metal hydroxides. Using the process of the present invention, an essentially closed loop process with respect to alkali metal may be envisioned.
  • the primary product is usually the sodium salt of salicylic acid.
  • SA is salicylate dianion.
  • Electrodialysis is a well known process, see for instance B. Elvers., et al., Ed., Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A16, VCH Verlagsgesellschaft mbH, Weinheim, 1990, p. 209-213 and 245-250, which is incorporated by reference herein. It is believed that because alkali metal hydroxide is generated in the electrolysis processes of the present invention and organic compounds are also present, fluorinated membranes, such as Nafion® Perfluorinated Membranes (from E. I. du Pont de Nemours and Company, Wilmington, Del. U.S.A.) are particularly useful in these and other electrodialysis processes.
  • fluorinated membranes such as Nafion® Perfluorinated Membranes (from E. I. du Pont de Nemours and Company, Wilmington, Del. U.S.A.) are particularly useful in these and other electrodialysis processes.
  • a three compartment cell (having cathode, center, and anode compartments) may be utilized in the process of the invention and which utilizes the dialkali metal salt of the aromatic hydroxycarboxylic acid. These starting materials are fed to the center compartment, while alkali metal hydroxide will be generated in the cathode compartment. In the anodic compartment oxygen and protons are generated, while in the center compartment the compound (OR 1 CO 2 )H y M 2 ⁇ y is generated.
  • Fresh solution of the dialkali metal salt may be added to the center compartment, and the solution of the center compartment removed, at such a rate so that “average” solute in the solution is (OR 1 CO 2 )H y M 2 ⁇ y , as defined herein, or two or more cells may be operated in series (the solution in the center compartment going from one cell to the next).
  • any of the salts of the aromatic hydroxycarboxylic acid present in the cell has a limited solubility in water, it may be desirable to heat the cell to increase the solubility in water. Limited solubility may be encountered especially when y is greater than 1, since “free” (not being an alkali metal salt) aromatic hydroxy carboxylic acid will be present, and the free organic compound may have only very limited solubility in cool water.
  • the pH of the solution in the center compartment is an indication of what the present value of y is in that compartment (see Comparative Example 1).
  • M is potassium and R 1 is p-phenylene it is preferred to carry out the process at a temperature of about 80° C. to about 105° C., especially when y is about 0.9 or more. More generally when y is about 0.9 or more it is also preferred to carry out the process at a temperature of about 80° C. to about 105° C.
  • the anion present in that compound has a conjugate acid whose pK a is about 2 or less (this pKa and the pH of the solution at 2.5 is measured in dilute solution without PHBA or its salts being present).
  • the conjugate acid of Q ⁇ is HQ, which has a pK a of about 2 or less.
  • the phosphate would exist predominantly as H 2 PO 4 ⁇ , whose conjugate acid is H 3 PO 4 .
  • the alkali metal salt present would be MH 2 PO 4 , wherein M is an alkali metal cation.
  • alkali metal present for each equivalent of ortho-phosphate containing anion.
  • Other useful anions include sulfate, oxalate, chloride, iodate, nitrate, and picrate (inorganic anions are preferred). Some anions may cause electrochemical side reactions at the anode. For instance, chloride may be oxidized to chlorine, which may cause other problems.
  • anion must have a conjugate acid with a pK a of about 2 or less is that if an anion that may potentially have more than one negative charge associated with it, at least one of the conjugate acids of all the potential anions must have a pK a of about 2 or less.
  • alkali metal cations are associated with the anion present at pH 2.5.
  • concentration of alkali metal cations associated with Q should be about 0.03 to about 4 molar, preferably about 0.05 to about 1.0 molar, and with a molarity of about 0.1 to about 0.3 especially preferred.
  • additional alkali metal cations present in the solution that are associated with other anions, such as the monoanion of the aromatic hydroxycarboxylic acid.
  • the second alkali metal compound referenced earlier herein may be added at any time to the solution containing the aromatic hydroxycarboxylic acid or its salts, but preferably before overvoltage starts to occur from increasing resistivity of this solution. This second compound may be added to this solution before it enters the electrolysis cell.
  • the alkali metal salt, or whatever form it is added in, should be present in sufficient amount so that as the cell approaches and reaches an actual pH of about 2.5 the concentration of alkali metal cation associated with it will be in the desired range.
  • This second alkali metal compound may be added directly in salt form, or in another form which will make the desired compound in situ.
  • alkali metal sulfate may be “added” as M 2 SO 4 , MHSO 4 or H 2 SO 4 . If bisulfate or sulfuric acid is added to a solution of the dialkali metal salt of the aromatic hydroxycarboxylic acid it will simply partially protonate the dialkali metal salt and form sulfate anion.
  • the aromatic hydroxycarboxylic acid may be isolated from the solution, for example by allowing the solution to cool and the product to precipitate.
  • the partition coefficient for most inorganic salts of alkali metal cations between the aqueous phase and the solid aromatic hydroxycarboxylic acid is believed to greatly favor the salt remaining in the aqueous phase (although one should preferably avoid inclusions of the aqueous phase in the precipitate). This means that a relatively pure form of the aromatic hydroxycarboxylic acid can be obtained which is especially low in alkali metal ion content.
  • the aqueous phase (including the second alkali metal compound) may be recycled in the electrodialysis process by dissolving new dialkali salt of the aromatic hydroxycarboxylic acid in it and electrodialyzing it.
  • some of the second alkali metal compound may be “lost” by electrolysis. If the aqueous phase is to be recycled, some makeup alkali metal second compound may be added to the aqueous phase in order to keep the concentration of the second alkali metal compound at the desired value. This can be done before or after the dialkali metal salt of the aromatic hydroxycarboxylic acid is dissolved in the aqueous phase.
  • R 1 is p-phenylene, o-phenylene, or 2,6-naphthylene (and p-phenylene is most preferred). It is always preferred with any hydroxycarboxylic acid that the alkali metal cation of the second compound is the same as the alkali metal cation of the dialkali metal salt of the aromatic hydroxycarboxylic acid.
  • R 1 is p-phenylene or 2,6-naphthylene it is preferred that M is potassium, and when R 1 is o-phenylene it is preferred that R 1 is sodium.
  • the concentration of the alkali metal salt of the aromatic hydroxycarboxylic acid in the aqueous solution that is electrodialyzed is not critical, but preferably not so high that free aromatic hydroxycarboxylic acid will crystallize out in the three compartment cell. However, it is preferred that the concentration is high enough so that the solution will readily conduct electricity. It is also preferred that the solution concentration be relatively high so that isolation of the free aromatic hydroxycarboxylic acid after electrolysis is simplified. Isolation may be accomplished by cooling the solution and separating the crystallized aromatic hydroxycarboxylic acid.
  • the filtrate containing some dissolved aromatic hydroxycarboxylic acid may be recycled back into the electrodialysis, i.e., “new” alkali metal salt may be dissolved in the filtrate and the solution electrodialyzed.
  • a preferred concentration of alkali metal salt in solution is about 10 to about 35 percent by weight, more preferably about 12 to about 25 percent by weight, of free aromatic hydroxycarboxylic acid based on the total weight of water and free aromatic hydroxycarboxylic acid equivalent in the solution.
  • the electrodialysis cell used was an ElectroCell AB (S-184 00 Akersberga, Sweden) “Electro MP Cell” configured as two 3-compartment cells sharing a single double sided anode arranged in parallel with respect to both electrical and process flows (see FIG. 1 ).
  • Nafion® N350 semipermeable membranes (commercially available from E. I. du Pont de Nemours and Company, Wilmington, Del. U.S.A.) were used to separate the compartments of the electrodialysis cells.
  • the nominal thickness of the membranes was 0.25 mm and they were preconditioned to the protonated form before initial use.
  • the effective area of each anode and cathode surface was 0.01 m 2 .
  • the anode was a dimensionally stable oxygen anode (DSA), and the cathodes were nickel metal plates.
  • DSA dimensionally stable oxygen anode
  • the anolyte, catholyte, and process reactor flasks are labeled 1 , 2 , and 3 , respectively, and are heated by heating jackets 4 , 5 , and 6 , respectively.
  • the anolyte, catholyte, and process fluids are circulated through lines 7 , 8 , and 9 , respectively, by pumps 10 , 11 , and 12 , respectively, through 3-compartment electrodialysis cell 13 (which represents two 3-compartment cells connected in parallel, as described above), and back to reactor flasks 1 , 2 , and 3 , respectively.
  • Heated fluid passing through heating jackets 4 and 5 using line 14 is heated by heater 15
  • heated fluid passing through heating jacket 6 and heating jacket 16 (which beats purge tank 19 ) using line 17 is heated by heater 18 (pumps not shown for heating lines).
  • Anolyte 1.800 l distilled water and 100 g of concentrated (100% by weight) sulfuric acid were mixed together and charged into a 3 liter jacketed glass anolyte reactor flask 1 .
  • Catholyte 2.123 1 of distilled water were mixed with 271 g of KOH/water mixture (45 wt % KOH) and charged into a 3 liter jacketed glass catholyte reactor flask 2 .
  • Process Fluid 1.691 l of distilled water were mixed with 487 g of KOH/water mixture (45 wt % KOH). Next, 540 g of PHBA were slowly added into this mixture with stirring. The mixture was heated to about 50° C. to facilitate dissolution of the PHBA. When the PHBA was completely dissolved, 68 g of KHSO 4 dissolved into 100 ml of distilled water were added to the mixture and the resultant solution was poured into a 31 jacketed glass process reactor flask 3 .
  • Each of the reactor flasks 1 , 2 , and 3 was heated by circulating hot water, and had its own circulating pump 10 , 11 , and 12 , respectively, to deliver solution to the appropriate section of the electrodialysis cell 13 as shown in FIG. 1 .
  • Circulating water temperatures were set to maintain a temperature of about 90° C. in the three reactor flasks 1 , 2 , and 3 .
  • Two individual power supplies (not shown) permitted independent adjustment of the voltage applied to each cell of 13 in case there were significant differences in internal resistance. In this way constant current flows of 15 amperes was maintained to each cell through the length of each experiment (except for the few minutes at the end of the experiment where cell voltages increased dramatically due to gas blinding of the membranes.
  • the pH in the process fluid reactor flask 3 was continuously monitored by a Cole-Parmer pH electrode (Model # JU-05994-27) suspended in the process fluid. Hydrogen and oxygen formed during the electrolysis were vented from high point vents (not shown) in each of their respective circulating streams (hydrogen from catholyte, oxygen form anolyte). A small amount of water was added to the reactor flask 1 at about mid point in the run to make up for losses due to electroosmotic transport of water through the semipermeable membranes.
  • the preparative technique was the same as that for Example 1 except that the process fluid was prepared by mixing 1.341 l of distilled water, 974.7 g of 45% KOH in water solution, and 540 g of PHBA in a flask. The mixture was then heated to about 50° C. and stirred until the solids were fully dissolved. The resulting solution was transferred to the reactor flask 3 as described above. No sulfate ion was present in the process fluid. Cell voltage and pH as a function of time are presented below:

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100140092A1 (en) * 2008-12-04 2010-06-10 Palo Alto Research Center Incorporated Flow de-ionization using independently controlled voltages
US9546342B1 (en) 2015-03-19 2017-01-17 Inveture Renewables, Inc. Complete saponification and acidulation of natural oil processing byproducts
US9745541B1 (en) 2016-09-09 2017-08-29 Inventure Renewables, Inc. Methods for making free fatty acids from soaps using thermal hydrolysis followed by acidification
US10975328B2 (en) 2018-11-06 2021-04-13 Inventure Renewables, Inc. Methods for making free fatty acids and fatty acid derivatives from mixed lipid feedstocks or soapstocks

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4508548B2 (ja) * 2003-04-28 2010-07-21 上野製薬株式会社 芳香族ヒドロキシカルボン酸の製造方法

Citations (7)

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Publication number Priority date Publication date Assignee Title
GB1030969A (en) 1964-04-29 1966-05-25 United States Borax Chem Improvements in or relating to the preparation of weak acids from their salts by electrodialysis
US4092230A (en) 1977-03-10 1978-05-30 Suntech, Inc. Electrochemical process for the manufacture of terephthalic acid
JPS649954A (en) 1987-07-03 1989-01-13 Idemitsu Petrochemical Co Production of hydroxybenzoic acid
JPH0411492A (ja) 1990-04-28 1992-01-16 Mitsubishi Electric Corp 投写型表示装置
WO1993025299A1 (de) 1992-06-17 1993-12-23 Basf Aktiengesellschaft Verfahren zur elektrochemischen herstellung von dicarbonsäuren
US5282939A (en) * 1988-09-20 1994-02-01 Basf Aktiengesellschaft Removal of salts by electrodialysis
WO1997037751A1 (en) 1996-04-08 1997-10-16 E.I. Du Pont De Nemours And Company Process for isolation of dicarboxylic acids and hydroxycarboxylic acids

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1030969A (en) 1964-04-29 1966-05-25 United States Borax Chem Improvements in or relating to the preparation of weak acids from their salts by electrodialysis
US4092230A (en) 1977-03-10 1978-05-30 Suntech, Inc. Electrochemical process for the manufacture of terephthalic acid
JPS649954A (en) 1987-07-03 1989-01-13 Idemitsu Petrochemical Co Production of hydroxybenzoic acid
US5282939A (en) * 1988-09-20 1994-02-01 Basf Aktiengesellschaft Removal of salts by electrodialysis
JPH0411492A (ja) 1990-04-28 1992-01-16 Mitsubishi Electric Corp 投写型表示装置
WO1993025299A1 (de) 1992-06-17 1993-12-23 Basf Aktiengesellschaft Verfahren zur elektrochemischen herstellung von dicarbonsäuren
WO1997037751A1 (en) 1996-04-08 1997-10-16 E.I. Du Pont De Nemours And Company Process for isolation of dicarboxylic acids and hydroxycarboxylic acids

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Hakushi et al., Ion-exchange membranes XXIV. Electrodialytic concentration of carboxylic acids using ion-exchange resins, STN Chemical Abstracts, Jan. 1, 1974, vol. 4(141) XP002121544.
International Search Report (PCT/US99/15305) dated Jul. 7, 1999.
Lindsey, A. S., et al., The Kolbe-Schmitt Reaction, Chem. Rev., vol. 57, pp. 583-620.

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100140092A1 (en) * 2008-12-04 2010-06-10 Palo Alto Research Center Incorporated Flow de-ionization using independently controlled voltages
US8404093B2 (en) * 2008-12-04 2013-03-26 Palo Alto Research Center Incorporated Flow de-ionization using independently controlled voltages
US8652314B2 (en) 2008-12-04 2014-02-18 Palo Alto Research Center Incorporated Flow de-ionization using independently controlled voltages
US9546342B1 (en) 2015-03-19 2017-01-17 Inveture Renewables, Inc. Complete saponification and acidulation of natural oil processing byproducts
US9745541B1 (en) 2016-09-09 2017-08-29 Inventure Renewables, Inc. Methods for making free fatty acids from soaps using thermal hydrolysis followed by acidification
US10975328B2 (en) 2018-11-06 2021-04-13 Inventure Renewables, Inc. Methods for making free fatty acids and fatty acid derivatives from mixed lipid feedstocks or soapstocks

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TW508351B (en) 2002-11-01
CA2335803A1 (en) 2000-01-13
EP1095004A1 (en) 2001-05-02
KR20010053415A (ko) 2001-06-25
WO2000001653A9 (en) 2001-06-28
JP2002519198A (ja) 2002-07-02
WO2000001653A1 (en) 2000-01-13
AU5091699A (en) 2000-01-24

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